It is often necessary or desirable to print alphanumeric information, as well as designs and logos on a variety of elongated members, such as tubing. The information to be printed typically depends upon one or more characteristics of the elongated member or a characteristic of an element with which the elongated member is to be used. For example, in the case of tubing, the information to be printed may depend on the diameter, wall thickness, material, color or other characteristic of the tubing. In addition, it may be desirable to utilize the printing apparatus only in connection with authorized tubing for the printing apparatus.
One prior art printing apparatus for tubing employs a hot stamp which forces a foil against a tube to form, in effect, a brand on the tubing. This technique requires a change of type or die for different sizes of lettering that may be required for different diameters of tubing. Also, the type or dies must be changed for languages employing different characters, as well as for designs and logos.
Dot impact printers have also been used for printing on tubing. With this technique, dots are extended against a ribbon to transfer pigment to the tubing, and the printhead is required to traverse across the tubing during the printing operation. In addition it is sometimes difficult to print characters, such as oriental characters, on tubing of small diameter.
For flattened tubing, a daisy wheel printer can be used. However, this requires wheel changes for size and language changes and is generally subject to the disadvantages noted above for the hot-stamp technique.
In the field of labelling it is known to weigh a product and have a computer command a printer to print the weight of the product on the label for that product.
Thermal printheads are available and have the advantage of being controllable with a microprocessor. Thermal printheads are usable in a variety of applications, including facsimile and ticket machines, various printers, including label and bar printers, data recorders, various instruments, word processors and typewriters. However, insofar as I am aware, thermal printers have not been used for printing on tubing.
Typically, thermal printers are used to print on paper. It is known for an operator to key into a microprocessor information that the thermal printer is to print. This creates the possibility of operator error and requires the attendance of the operator to perform this function.